Organic Teaching Laboratory Research Articles

Green chemistry principles in the organic teaching laboratory: an environmentally benign synthesis of banana oil and aspirin

В этом исследовании рассматривается, как курсы органической химии для студентов бакалавриата могут включать концепции зеленой химии. В нем дается краткое изложение результатов и объясняется обоснование интеграции экологически безопасных практик в образование. Цель статьи – продемонстрировать возможные преимущества включения тем зеленой химии на фундаментальный уровень преподавания органической химии путем изучения стратегий преподавания и предоставления тематических исследований. Особое внимание уделяется преобразующему влиянию интеграции на обучение студентов и более широкий экологический ландшафт, который способствует более устойчивому и экологически чистому подходу к химическому образованию. В статье приведены примеры лабораторных занятий, демонстрирующие применение концепций зеленой химии при синтезе бананового масла и ацетилсалициловой кислоты. Благодаря этим экспериментальным работам укрепляются теоретические знания учащихся по стереохимии, реакционным процессам, синтезу и анализу органических молекул. В частности, синтез аспирина и изоамилацетата помогает объяснить процессы реакций этерификации и ацетилирования. Кроме того, демонстрируя основные методы, такие как экстракция, отгонка и перекристаллизация, эксперименты такого типа помогают студентам бакалавриата стать более опытными в лабораторных условиях.

Synthesis of a Diaryliodonium Salt and Its Use in the Direct Arylation of Indole: A Two-Step Experiment for the Organic Teaching Laboratory

In the past decade, C–H functionalization has been a very active topic of research in both academia and industry. When a H atom is replaced by an aryl (or heteroaryl) group, the transformation is t...

Chemical Exploration with Virtual Reality in Organic Teaching Laboratories

While virtual reality (VR) is emerging as an interactive tool for chemical education, its application and assessment for chemical education are still limited. Thus, an educational VR activity based...

Systems Thinking and Green Chemistry: Powerful Levers for Curricular Change and Adoption

Curricular change within the chemistry curriculum is often difficult and slow, in part because there are numerous specific barriers to implementation. However, a larger issue is that the curriculum, and the institutions that it is connected with, are complex systems. In the implementation of a new green chemistry curriculum for the organic teaching laboratory, we employed a systems-thinking approach to develop and disseminate the new curriculum. We identified five key leverage points where targeted efforts could yield significant gains in the design and implementation of the curriculum. Two key strategies that emerged from these efforts were the importance of expanding system boundaries to garner support for our efforts and building capacity of faculty to participate in curricular change. The systems approach contributed significantly to the successful introduction of green organic chemistry into the curriculum. Systems-based strategies are likely to catalyze future curricular-change efforts throughout the curriculum.

Synthesis of an Imidazolidinone Organocatalyst and Its Application in a Diels–Alder Cycloaddition: A Multistep Experiment for the Organic Teaching Laboratory

The development of novel, high-yielding, and selective methodologies for the asymmetric synthesis of stereocenters is at the forefront of modern synthetic chemistry research. Organocatalysis can now be viewed as a viable alternative to the use of the sometimes toxic transition-metal catalysts. In this experiment, the simple synthesis of an achiral imidazolidinone organocatalyst is described and its performance is compared to that of a related commercially available chiral catalyst in a Diels–Alder cycloaddition. The organocatalyst operated via an iminium ion intermediate and the product of the Diels–Alder cycloaddition was purified by silica plug filtration (no flash column chromatography required). The diastereoselectivity was readily measured with 1H NMR spectroscopy and optionally, the enantioselectivity of the chiral catalyst can be assessed with chiral GC. The experiment can be performed over three laboratory sessions and is suitable for a third- or fourth-year undergraduate laboratory curriculum. Th...

PREPARATION OF 1,2,4-OXADIAZOLES: TEACHING-LEARNING SEQUENCE APPLIED TO THE COURSE ON ORGANIC SYNTHESIS IN UNDERGRADUATE STUDIES

1,2,4-oxadiazoles are used in a wide range of applications, including medicinal chemistry and chemistry of materials. However, this kind of oxadiazoles is not usually prepared in an undergraduate organic teaching laboratory. This work describes a didactic sequence for the preparation of 1,2,4-oxadiazols, mediated by microwave irradiation, employing home-use microwave oven. For the development of this practice, one lecture and one laboratory session were used. At the end of this session, a questionnaire was applied to evaluate the didactic sequence. The conclusion was that this approach can be used for the preparation of 1,2,4-oxadiazoles as a pedagogical practice to make the process of teaching easier and enjoyable.

Paper Chromatography and UV–Vis Spectroscopy To Characterize Anthocyanins and Investigate Antioxidant Properties in the Organic Teaching Laboratory

A variety of fruits and vegetables, including raspberries, blueberries, Concord grapes, blackberries, strawberries, peaches, eggplant, red cabbage, and red onions, contain flavonoid compounds known as anthocyanins that are responsible for the blue-red color and the astringent taste associated with such foods. In addition, anthocyanins exhibit a wide range of chemical properties, such as radical scavenging, metal chelation, pH-dependent color changes, and intramolecular stabilization. Two experiments have been developed for anthocyanin-containing extracts isolated from freeze-dried berries to teach students the skills of solid–liquid extraction, paper chromatography, UV–vis spectroscopic characterization, and detection and evaluation of radical scavenging properties.

Mass Spectrometry in Organic Synthesis: Claisen–Schmidt Base-Catalyzed Condensation and Hammett Correlation of Substituent Effects

Undergraduate laboratories generally teach an understanding of chemical reactivity using bulk or semimicroscale experiments with product isolation and subsequent chemical and spectroscopic analysis. In this study students were exposed to mass spectrometry as a means of chemical synthesis as well as analysis. The ionization method used, paper spray, is rapid and can be coupled with online analysis (by mass spectrometry) or off-line analysis (e.g., thin layer chromatography). Chemical synthesis in the course of paper spray ionization takes advantage of the accelerated reaction rates associated with changes in pH and reagent concentrations. Such changes arise from solvent evaporation from charged microdroplets. In these experiments students contrasted paper spray techniques with traditional bulk synthetic methods for the Claisen–Schmidt base-catalyzed condensation. From mass spectral data obtained during the laboratory session, students were able to model electronic effects of substituents on reaction rates. Experimental procedures tailored to the undergraduate organic teaching laboratory are provided.

Green Aqueous Wittig Reaction: Teaching Green Chemistry in Organic Teaching Laboratories

Green experiments in the organic teaching lab are a vital part of training a new generation of scientists. Not only do they make the lab experience safer and produce less costly waste, they allow students an opportunity to examine and consider potentially hazardous chemical methodologies and develop alternatives. The work discussed here focuses on a series of Wittig reactions that are carried out in aqueous conditions, at room temperature, and in less than one hour. The reactions have been applied to a variety of starting aldehydes. Results for this work and strategies for implementing a green chemistry case study into the laboratory curriculum are presented.

A Research Module for the Organic Chemistry Laboratory: Multistep Synthesis of a Fluorous Dye Molecule

A multi-session research-like module has been developed for use in the undergraduate organic teaching laboratory curriculum. Students are tasked with planning and executing the synthesis of a novel fluorous dye molecule and using it to explore a fluorous affinity chromatography separation technique, which is the first implementation of this technique in a teaching laboratory. Key elements of the project include gradually introducing students to the use of the chemical literature to facilitate their searching, as well as deliberate constraints designed to force them to think critically about reaction design and optimization in organic chemistry. The project also introduces students to some advanced laboratory practices such as Schlenk techniques, degassing of reaction mixtures, affinity chromatography, and microwave-assisted chemistry. This provides students a teaching laboratory experience that closely mirrors authentic synthetic organic chemistry practice in laboratories throughout the world.

Synthesis of a Fluorescent Conjugated Polymer in the Undergraduate Organic Teaching Laboratory

Fluorescent organic polymers are used in a wide range of applications, including explosive sensing, clean energy technologies, and biological detection schemes. However, such polymers are rarely synthesized in an undergraduate organic teaching laboratory due to their air and moisture sensitivity. The synthesis of a fluorescent organic polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), is described for the upper-division undergraduate organic laboratory. This polymerization is accomplished using straightforward procedures to exclude air and moisture, without requiring the use of a glovebox or strict inert-atmosphere conditions. Once synthesized, the polymer is used for two applications, the fabrication of fluorescent thin films and the formation of organic conjugated nanoparticles, and leads to a number of pedagogical opportunities about polymerization, organic fluorescence, solid-state properties, and hydrophobic nanoparticle formation.

A Survey of the Practices, Procedures, and Techniques in Undergraduate Organic Chemistry Teaching Laboratories

A survey was conducted of four-year institutions that teach undergraduate organic chemistry laboratories in the United States. The data include results from over 130 schools, describes the current practices at these institutions, and discusses the statistical results such as the scale of the laboratories performed, the chemical techniques applied, the instrumentation available, the laboratory equipment used, the chemistry topics covered, the way chemical safety is presented, and how chemical waste is handled. These results provide a “snapshot” of the current state of the undergraduate organic teaching laboratory.

Green Reductive Homocoupling of Bromobenzene

Although transition-metal-catalyzed reactions are important in contemporary organic chemistry, relatively few resources for the second-year organic chemistry curriculum discuss the subject. The inquiry-based experiment described here, an iron-catalyzed preparation of biphenyl from bromobenzene, introduces this topic. The reaction uses an inexpensive and relatively benign iron precatalyst that is air- and moisture-stable, and the experiment can be performed using the equipment found in a typical organic teaching laboratory. The crude product can be analyzed by melting point determination or by gas chromatography. The experiment allows for a general discussion of redox cycles common in many metal-catalyzed reactions, redox processes of organic substrates, and green chemistry. The experiment can be used in organic or inorganic laboratories.

Oxidation of Borneol to Camphor Using Oxone and Catalytic Sodium Chloride: A Green Experiment for the Undergraduate Organic Chemistry Laboratory

A new green oxidation procedure was developed for the undergraduate organic teaching laboratories using Oxone and a catalytic quantity of sodium chloride for the conversion of borneol to camphor. This simple 1 h, room temperature reaction afforded high quality and yield of product, was environmentally friendly, and produced negligible quantities of hazardous waste. The experiment was performed using (1S)-borneol providing large quantities of the less prevalent (1S)-camphor, which is useful in a research setting. A survey of the students indicated a high level of satisfaction in the green qualities of the reaction and the use of their collected product in fundamental research. This new experiment proved superior to the former bleach oxidation procedure previously used as an illustrative green reaction in these labs.

Microwave-Assisted Organic Synthesis in the Organic Teaching Lab: A Simple, Greener Wittig Reaction

A greener, microwave-assisted Wittig reaction has been developed for the second-semester organic teaching laboratory. Utilizing this microwave technique, a variety of styrene derivatives have been successfully synthesized from aromatic aldehydes in good yields (41–68%). The reaction not only occurs under neat reaction conditions, but also employs an inexpensive, non-pyrophoric base and readily available glassware. The average reaction times have been reduced to a matter of minutes rather than the hours typical of literature procedures. This method will therefore provide a quick and easy example of a Wittig reaction that can be accomplished in any undergraduate organic lab. The mixture of cis and trans alkenes produced by this method also provides instructors with opportunities to emphasize spectroscopic analysis of product mixtures.

The State of Organic Teaching Laboratories

This review explores the dramatic changes that have taken place in the organic chemistry laboratory course over the last two to three decades. The most significant changes have been in the areas of pedagogy and technology. Significant inroads have been made towards combating student cookbooking, particularly through the design of discovery-based or puzzle experiments, as well as through inquiry and project-based experiments. The extent to which microscale-level work has spread can only be described as revolutionary. Modern spectroscopic instrumentation has transformed the organic laboratory environment. Molecular modeling has opened up new possibilities for student exploration of regioselectivity, stereoselectivity, and molecular conformation.

The Evolution of a Green Chemistry Laboratory Experiment: Greener Brominations of Stilbene

We describe two new greener alkene bromination reactions that offer enhanced laboratory safety and convey important green chemistry concepts, in addition to illustrating the chemistry of alkenes. The two alternative reactions, one involving pyridinium tribromide and a second using hydrogen peroxide and hydrobromic acid, are compared to the traditional bromination of stilbene through the application of green metrics, including atom economy, percent experimental atom economy, E factor, and effective mass yield. The use of these metrics to guide experiment evaluation and optimization in the teaching lab environment is examined. The development of these new experiments provides (i) an ideal case study for demonstrating the process of on-going evaluation and modification of experiments that leads toward more environmentally benign educational materials for the undergraduate organic teaching laboratory and (ii) a concrete example useful for introducing the practical use of metrics to students as a part of their...

Green Chemistry in the Organic Teaching Laboratory: An Environmentally Benign Synthesis of Adipic Acid

Environmentally benign ("green") chemical techniques are growing in importance in academic and industrial research laboratories. Such chemistry has been slow to appear in teaching laboratories, owing in part to a lack of published material on this subject. Recent developments in green synthesis provide opportunities to introduce this material in teaching laboratories. We present a synthesis of adipic acid that utilizes green reagents (hydrogen peroxide as the oxidant), solvents (water), and methods (phase-transfer catalysis, catalyst recycling). The synthesis works well and provides an excellent forum for emphasizing green chemical concepts while teaching laboratory skills. It demonstrates reuse of a product, synthesis using a nonhazardous solvent, elimination of deleterious by-products, and use of a recyclable catalyst. It can be carried out on either the macroscale or microscale and generates little waste if the catalyst solution is recycled. This experiment fits well in a sophomore organic sequence; it covers the topics of oxidation, phase-transfer catalysis, and the technique of recrystallization, reinforces lecture topics such as alkene synthesis and reactivity, and provides an opportunity to introduce polymer chemistry.

"Double Unknown" Microscale Preparation and COSY Analysis of an Unknown Ester: An Introductory 2D-NMR Experiment

2D-NMR experiments are becoming more commonplace for organic analysis and promise to become as routine for chemists of this decade as 1D-NMR experiments were for chemists of the 1970's. However, undergraduate students seldom if ever are exposed to such experiments despite the increasing availability of high-field, superconducting magnets, more powerful computers, and menu driven software that is extremely friendly. This article outlines an experiment that integrates NMR into the organic teaching laboratory in a way designed to highlight the power of the technique and not merely to confirm the identity of known substances.

Flameless organic teaching laboratories are safer

A timely goal for many colleges is to make the laboratory completely flameless by the sue of electric heating equipment; includes descriptions of important electrical accessories, the benefits of eliminating bunsen burners, and hazards remaining in a flameless laboratory.